Ryan Tubridy stepped down as host of the Late Late Show earlier this year.
RTÉ paid Ryan Tubridy 345,000 euro more than declared from 2017 to 2022.
The state broadcaster has described it as a "serious breach of trust".
A review was carried out by Grant Thornton into RTÉ's accounts - which was discussed by the board of the broadcaster on Monday.
It found payments totaling 345,000 euro were paid to Ryan Tubridy between 2017 and 2022 - over what was made public.
The review found RTÉ had guaranteed additional payments to the former Late Late Show host through commercial partners - in exchange for appearances.
Figures released by the broadcaster show Tubridy was paid in excess of €500,000 between 2017 and 2022 - despite his salary being declared below half a million.
Ryan Tubridy stepped down as host of the Late Late Show earlier this year.
The RTÉ board has apologised
Motorists Are Being Reminded Not To Drink And Drive This Stephen's Night
Nearly 8 In 10 People Cite Money As The Cause Of Stress During The Christmas Period
The Train Line Between Dublin's Connolly And Grand Canal Dock Will Close Today Until The 5th Of January
ISPCC Reveals That For Many Children In Ireland, Christmas Was A Day Of Trauma And Despair
Locals Urged To Check In On Elderly Relatives And Neighbours Over The Festive Period
Man Arrested In Connection With Fatal Hit-And-Run Incident In Limerick
Man Dead After Car Enters Grand Canal In Kilmeague
The Newbridge-Kildare Samaritans Branch Have Launched This Year's Longest Night Campaign
